Yes many things can be said, and both are true. Diversity is necessary, well established standards also...
I think the wisdom would be to try to combine the two.
As example, what misses now, who have 3 can have 4, is a new X project that combines some of the possible best features of all, yet maintains the X standard but is flexible enough to allow some extensibility =diversity.
I trace parallels with compiz/fusion and the all WM developments. It was nice to be able to change WMs, it will be nice to keep that possibility, yet all could function in the same system, and no need to "force" changes to the apps -> you have diversity, and you have a standard.